1. Electric field analysis for predicting the distribution of multiple cracks by means of direct current electrical potential methodCrack-current modification method was proposed for analyzing the electric field around multiple cracks. Electric field analysis was carried out for randomly distributed disk-shaped cracks in a three-dimensional conductor and for distributed through-cracks in a two-dimensional one. Based on the results of the analysis, a procedure was proposed for predicting the distribution of multiple cracks by direct current electrical potential method.2. Evaluation of a small defect existing right under the surface of conductive materialsA small defect existing right under the surface of the conductive material was evaluated by means of a scanning probe microscone with current measuring system where electric current was supplied through a cantilever to the conductor and the defect was evaluated by the change in the current. Electric analysis was carried out for discussing the basis of this apparatus by the crack-current modification method which was used for the electric field analysis around multiple cracks. It was clarified by actual current measurement that contact condition or contact electric resistance between the cantilever and the specimen has a great influence on the amount of current. In order to find the best measuring condition, electric analysis was carried out simulating the apparatus in which the contact area was fluctuated intentionally. The following results were obtained. Modification of the shape of a cantilever tip is necessary. Further development is needed on the servomechanism of cantilever.